MANILA - An outbreak of measles, first declared in Metro Manila and Central Luzon, was also observed in another Luzon region and 2 areas in Visayas, which tallied an increase in cases of the disease, the health department said Thursday.

The outbreak declaration has been expanded to Calabarzon, Western Visayas, and Central Visayas, the agency said in a statement.

The wider outbreak declaration aims to "strengthen surveillance of new cases and alert mothers and caregivers to be more vigilant," Health Secretary Francisco Duque III told reporters.

As of Jan. 26, Calabarzon tallied 575 measles cases and 9 deaths, said DOH.

Meanwhile, Western Visayas had 104 cases and 3 deaths and Central Visayas had 71 cases and 1 death.

Metro Manila logged 441 cases and 5 deaths while Central Luzon had 192 cases and 4 deaths, DOH said.

This contradicts data from San Lazaro hospital in Manila which recorded 55 deaths since January, with most of the fatalities aged 3 months to 4 years old.

The health department needs to validate reported deaths before including these in the tally, said Duque.

"Marami ring pinanggalingan itong mga datos, we need to validate them. Hindi naman puwedeng kung ano lang ang bilang na pumapasok, iyun na ang ating ibubukang bibig," he said.

(The data come from multiple sources, we need to validate them. We cannot immediately parrot the figures that come in.)

Other regions under "close watch" were Mimaropa with 70 measles cases, Ilocos with 64 cases, Northern Mindanao with 60 cases, Eastern Visayas with 54 cases and Soccsksargen with 43 cases, said DOH.

"These regions should likewise step up their response against this highly communicable disease," Duque said.

Measles, caused by a virus that infects the respiratory tract, can be passed through direct contact and through the air. Its complications include severe diarrhea, pneumonia, blindness, and even death, according to the Department of Health.

Symptoms of measles include fever, reddening of the eyes, cough and colds, and red rashes, the agency added.

Unvaccinated children aged 5 and below are at highest risk of the disease, Health Undersecretary Eric Domingo earlier said. Measles vaccine is usually given to children aged 6 months and above, and parents of those younger must be extra cautious.

Free vaccine against measles is available in government hospitals and health centers.

However, an opinion poll by the London School of Hygiene and Tropical Medicine last year showed just 32 percent of 1,500 Filipinos surveyed trusted vaccines, down from 93 percent in 2015.

Low trust in the government's immunization drive may be attributed to anti-dengue vaccine Dengvaxia, which French drug maker Sanofi admitted could trigger more severe symptoms in some cases, Duque earlier said.

The Dengvaxia issue should not muddle trust for other vaccines, the efficacy of which have been proven for decades, said the health chief.

Report from Raphael Bosano, ABS-CBN News